Movable gate system for a hydraulic dam

ABSTRACT

A device for operating at least one shutter of a movable dam comprises an oscillating guide pivoted on a horizontal pin which is attached to the body or floor of the dam, a push-rod capable of translational motion with respect to the oscillating guide and an abutment member which is orientable about a horizontal shaft attached to the shutter, the abutment member being adapted to receive the extremity of the push-rod which is applied against the abutment member during operation of the shutter.

United States Patent 1 1 Aubert Dec. 4, 1973 MOVABLE GATE SYSTEM FOR A HYDRAULIC DAM [76] Inventor: Jean Aubert, 8, rue La Boetie, Paris,

France [22] Filed: Aug. 1, 1972 [21] Appl. No: 277,111

[30] Foreign Application Priority Data Aug. 5, 1971 France 7128734 [52] U.S. Cl. 61/26 [58] Field of Search 61/22, 25, 26, 18

[56] References Cited UNITED STATES PATENTS 419,287 1/1890 Scaife 61 26 3,107,722 10/1963 Larsson..." 160/188 3,338,057 8/1967 Eckstine 61/25 3,509,724 5/1970 Turner 61/25 FOREIGN PATENTS OR APPLICATIONS 207,220 2/1909 Germany 61 /26 949,875 9/1956 Germany 61/25 1,459,403 8/1968 Germany 61/25 Primary Examiner-Mervin Stein Assistant Examiner-Philip C. Kanman Attorney-Irvin S. Thompson et a1.

[ 5 7 ABSTRACT A device for operating at least one shutter of a movable dam comprises an oscillating guide pivoted on a horizontal pin which is attached to the body or floor of the dam, a push-rod capable of translational motion with respect to the oscillating guide and an abutment member which is orientable about a horizontal shaft attached to the shutter, the abutment member being adapted to receive the extremity of the push-rod which is applied against the abutment member during operation of the shutter.

12 Claims, 9 Drawing Figures PATENTED 4 7 SHEET 3 BF 4 vIII/llll HP Fig, 7

MOVABLE GATE SYSTEM FOR A HYDRAULIC DAM This invention relates to a movable gate system for a hydraulic dam.

It is known that a dam consists of a mass of masonry which is anchored in the" ground and constitutes the body of the darn when this latter has a massive structure of the floor of the dam when it is constructed in the form of a slab or plate. The floor is placed between twoabutments and in some structures is divided into sections by piers, provision being made for movable elements disposed between the piers and constituting the so-called gate. The massive body of a dam can also be surmounted by a movable gate.

Some gate systemswhich are already known consist of juxtaposed elements of small size which can be displaced independently of each other. These elements can take up a practically vertical end position, a second and substantially horizontal end position and in many instances can also take up intermediate positions.

Movable gate elements of this type can be constituted by a wicket or shutter panel which is pivotally attached to the floor or the body of the dam and maintained in the different positions mentioned above by means of a prop supported on stop catches which are secured to the floor or to the body of the darn.

In another known design, the movable gate elements comprise a tie-frame or horse which is pivoted to the floor or to the body of the dam and a shutter panel which is in turn pivoted about a horizontal hinge-pin attached to the horse. In that case, the prop is pivoted to the horse.

In the following description, the movable shutter elemerits-of the type specified in the foregoing will be designated by the word shutter," this term being intended to refer not only to the shutter panel but also to the other movable components which are associated there with. Theterm applies both to the shutter panel which is pivoted directly to the floor and to the panel which is pivoted to a hinged horse, or to other juxtaposed and differently arranged elements having small dimensions.

This type of gate, which is constituted by small juxtaposed elements, has an advantage in that the piers or abutments can be spaced at a substantial distance from each other, thus forming wide navigable channels when the dam is open.

Moreover, by virtue of the additional degree of freedom of shutter panels which are pivoted to a horse, the danger of damage as a result of impact of a floating body and in particular of a boat is appreciably reduced. Finally, if it proves necessary to carry out the repair or replacement of a shutter, this can be effected by making use of a screen which bears on the adjacent elemerits. Unwatering of the floor by means of emergency cofferdams is therefore not necessary, with the result that the floor is not subjected to uplift pressures and can therefore be of more lightweight construction than the shutters consists in providing a top service bridge carrying a track and an operating carriage which runs along this latter. Said carriage is provided with mechanisms such as an articulated arm, cable or chain for engaging the shutter in order to raise or lower this latter.

Aside from the fact that it has sometimesgiven rise to criticism on the ground of unattractive appearance, this design solution has the disadvantage of high costtof construction, although less costly than dams of the type having large elements.

The primary aim of the invention is to overcome the disadvantages mentioned above by providing a shutteroperating means of rugged design which is low in construction cost and does not mar the appearance of. the landscape since the superstructure is completely eliminated.

In accordance with the invention, the movable gate system for a hydraulic darn, which comprises at least one shutter and one device for operating said shutter, is distinguished by the fact that the operating device comprisesan oscillating guide rotatably mounted with respect to a horizontal pin attached to the floor or to I the body of the dam, a push-rod movable in rectilineal translational motion with respect to said guide, means for displacing the push-rod with respect to the guide and an abutment member which is orientable about a horizontal shaft attached to the shutter, said abutment member beingadapted to receive the extremity of said push-rod which is applied against said member during an operation of said shutter.

It is thus possible to dispense with the top service bridge together with the operating carriage and ancillary equipment.

In a preferred embodiment of the invention, the oscillating guide and the movable push-rod are constituted respectively by the body and the rod of a main oil-actuated jack and the operating rod of the jack is withdrawn between two operations into the interior of the jack body in which said rod is immersed in the oil. The operating rod is thus protected against the action of the water except during the operations of the shutter which are of short duration. Said action of the water would be liable to result in oxidation of the jackoperating rodif the water were acid and in erosion if the water contained substances in suspension.

In an advantageous embodiment of the invention, the body of the main jack is mounted within a cavity formed in the body or the floor of the dam and said cavity isprotected by a hood provid-ed with only a narrow slot for permitting the jack-operating rod to pass therethrough. Said slot is in turn closed between two operations by means of an articulated cover. Thus, the jack is surrounded by practically motionless water andthere is noreason to fear any substantial muddeposits inside the cavity within which the jack is housed and in which this latter must be capable of undergoing a change of orientation;

In a preferred embodiment of the invention, the system comprises a device for locking the main jack body in position between two operations. This device is controlled in dependence on the supply of oil under high pressure to the jack, with the result that the locking action is suppressed automatically at the beginning of each operation. The system preferably comprises in addition a device for locking the abutment member of the shutter.

Between two operations, the jack body on the one hand and the abutment member of the shutter on the other hand accordingly retain the position which they had occupied at the end of a previous operation. At the beginning of another operation, the rod of the jack will therefore be oriented towards the abutment member which will in turn be suitably positioned for receiving said rod.

In the event that the shutter'is equipped with a horse, the abutment member is advantageously pivoted to this latter in order to reduce the danger of damage in the event of impact as has been stated earlier.

Further properties and advantages of the invention will become apparent from the detailed description which now follows.

A number of embodiments of the invention are illustrated in the accompanying drawings which are given by way of non-limitative example, and in which FIG. 1 is a vertical sectional view taken parallel to the direction of flow and showing a movable gate element in accordance with the invention, the shutter being in the raised position FIG. 2 is a view which is similar to FIG. 1 and in which the shutter is shown in the horizontal position of withdrawal FIG. 3 is a plan view with portions broken away and corresponding to FIG. 2

FIG. 4 is a view in elevation showing a device for locking the jack body of FIGS. 1 to 3;

FIG. 5 is a plan view to a smaller scale and corresponding to FIG. 4

' FIG. 6 is a transverse sectional view of a device for locking the orientable abutment member of the shutter of FIGS. 1 to 3 FIG. 7 is a plan view of the pivotally mounted abutment member of the shutter of FIGS. 1 to 3 FIG. 8 is a diagram of the oil supply to the jacks of FIGS.1to3and4to5;

, FIG. 9 is a vertical sectional view taken parallel to the direction of flow and showing a movable gate element in accordance with the invention, said element being mounted on the spillway crest of a stationary dam.

' There is shown in FIGS. 1 to 8 a movable gate element in accordance with the invention as applied to a movable dam, the gate of said dam being constituted by the juxtaposed assembly of similar elements.

It is known that a movable dam is the term customarily employed to designate a darn which is usually built across the bed of a watercourse, in which the assembly consisting of the movable portions constituting the gate 2 system has a large surface area. The stationary portions of these dams, the main function of which is to serve as a support or bearing for the gate, are usually constituted by a masonry floor 1 limited by two abutments with piers interposed in some cases between these latter.

A sill 2 is anchored to said floor 1 and supports a horizontal shaft 3 on which the shutter 4 is pivotally mounted. In the embodiment which is illustrated, said shutter comprises a horse 5 which is pivoted about the stationary shaft 3 and a shutter panel 6 which is in turn pivotally attached to the horse 5 in the vicinity of the mid-point of said panel. For the sake of clarity of the drawings, it is assumed that the shutter panel 6 has been partially broken away so as to leave only a bottom corner as shown in the plan view of FIG. 3, the lateral edge of said shutter panel being represented schematically by the chain-dotted line 7. Except in the event of impact, the lower portion of the shutter panel 6 is continuously applied against a sheet metal member which constitutes the upstream face of the sill 2. Said sheet metal member 8 is provided with recesses 9 (shown in FIGS. 2 and 3) in order that the horse 5 can be raised.

Said horse 5 comprises a rectangular frame strengthened by cross-bracing members (not shown). Aside from the components employed for pivotal attachment to the shaft 3, said frame is adapted to carry two sets of three brackets 11 (as shown in FIG. 3), each set being intended to support a pin 12 on which are pivotally mounted on the one hand the shutter 6 and, on the other hand, a lifting beam 13 in which is fixed the top end of a prop 14. The bottom end of said prop is applied against one of the stop catches 15 of a slide 16 of the type, for example, which is referred-to as a Pascaud hurter. The shutter 4 is capable of assuming a number of positions at different angles of inclination with respect to the horizontal plane, each of these positions being such as to correspond to one of the stop catches 15. When the shutter is completely lowered to the horizontal position (as shown in FIGS. 2 and 3), the bottom end of the prop l4 escapes from the catches of the hurter and the shutter rests on stops (not shown) which are supported by the floor 1.

In order to operate the shutter 4, the invention provides for a device comprising an oscillating guide 17 which is pivoted about a horizontal pin 18 attached to the floor 1, and a push-rod 19 which is capable of moving in rectilineal translational motion with respect to the oscillating guide 17. The operating device further comprises an abutment member 21, said member being orientable about a horizontal shaft which is attached to the horse 5 and being adapted to receive the extremity of the push-rod 19 which is applied against said member during the operations of the shutter.

In the embodiment shown, the oscillating guide 17 is constituted by the body of an oil-actuated main jack and the push-rod 19 is the operating rod of said jack.

The body 17 of the main jack is housed in a cavity 22 which is formed within the floor l. The cavity 22 is provided at the surface of the floor with a substantially rectangular opening 23 having a dimension in the direction at right angles to the axis of the jack which is only slightly greater than the diameter of the jack body so that this latter is accordingly permitted to oscillate about the pin 18 with provision for a small clearance with respect t the lateral walls of the cavity 22.

The opening 23 is surmounted by a shield hood 24, a narrow slot 25 through which the operating rod 19 of the main jack is permitted to pass being formed in the upstream wall of said hood which is directed towards the shutter 4. Said slot 25 can in turn be closed by a cover 26 which is hinged about a horizontal pin 20. When the operating rod 19 is fully withdrawn within the interior of the jack body 17 (as shown in FIG. 2), the cover 26 is lowered onto the slot 25 under the action of its own weight. Provision can also be made for a spring in order to assist the action of gravity in the closure of the cover 26.

The operating rod 19 of the main jack is connected to a piston which is movable within the body 17 and divides this latter into two chambers. Each chamber is connected by means of a system which will be described hereinafter to two ducts 27 and 28. The two chambers of the body 17 are continuously kept full of oil and the body 17 is so designed as to be capable of containing the full length of the operating rod 19 when this latter is in its withdrawn position (as shown in FIG. 2).

The abutment member 21 is constituted (see FIG. 7) by a shaped or sectional shaft which is provided at both ends with cylindrical shaft-journals 31 mounted injournal-bearings provided on the side-stringers of the horse 5. There is formed in the central portion of the abut- Y ment-member or shaft 21 a cavity 32 of substantially frusto-conical shape which is adapted to accommodate the extrem'ity of the operating rod 19 of the main jack.

.The shaft 21 is so dimensioned that its center of gravity 1 islocated in the vicinity of its geometrical axis of rota- .sake of enhanced clarity but are shown in FIGS. 4 to 6.

The jack body 17 is provided with two trunnions 33,

34 (shown in FIG. 5), these latter being mountedin trunnion-bearings 35 which are secured to the floor 1. The trunnion 34 has'an extension beyond the corresponding bearing so as to form a cylindrical portion 36 having a roughened surface. The common geometrical axis of the trunnions 33 and 34 corresponds to the pin 18 of FIGS. 1 and 2. The complete assembly consisting of trunnions and bearings is protected by means of sleeves 37 of the=hood 24 (as shown in FIG. 3).

An elbowed lever 38 pivoted about a horizontal pin 39 which is attached to the floor comprises a first arm 41 and a second arm 42 havinga roughened portion which is adapted to bear on the rough surface of the cylinder 36. Saidlever is particularly visible in FIG. 4 which has been drawn to a larger scale than FIG. 5.

The first arm of the lever 38 is subjectedto the action of bearing means which, in the embodiment shown, are constituted by a gravity block 43 whichis pivotally attached near the extremity of the arm 41. The device further comprises an oil-actuated auxiliary jack 44, the two compartments of which are supplied in parallel with those of the main jack. Said auxiliary jack is placed vertically beneath the gravity block 43 and the operating rod 45 of said jack is directed substantially vertically. The block 43 is provided with a cavity 46 having v a bottom opening and directed towards the operating rod 45 of the auxiliary jack.

The device for locking the pivotal abutment member 21 inposition comprises (as shown in FIG. 6) a member 47 which is secured to one side-stringer of the frame of the horse 5. Said member 47 has a face 48 of substantially cylindrical shape which is coaxial with a journal 31 of the shaft 21 and disposed in the vicinity of the periphery of said journal. Said face 48 is provided with recesses 49 in the shape of spherical cups and equal in number to the intended positions of the shutter 4. So far as concerns the shaft-journal 31, this latter is provided with a cavity 51 having an opening which is directed towards the member 47, there being housed within said cavity a ball 52 which is thrust back by a spring 53.

with the result that both the lower chambers and the upper chambers of the two jacks are at the same pres sure at each instant.

The pipes 63, 64 extend to an electrovalve 69 of a type which is known per se and which does not therefore need to be described in detaiLalthough it would also be possible to adopt another type of valve such as a hydrovalve, for example. The electrovalve 69 is also connected to the general supply ducts 27, 28 (shown also in FIGS. 1 and 2).

The electrovalve 69 comprises a slide-valve 71 pierced by two ducts 72, 73. The slide-valve 71 isactuated by an electromagnet 74 and can assume two positions. In the first position which is shown in FIG. 8, the pipes 63, 64 are connected to the general supply ducts 27, 28. In the second position of the slide-valve 71, the pipes 63, 64 are isolated from the general supply ducts.

The movable gate system is fitted in the majority of cases with a large number of juxtaposed shutters such as the shutter 4 which areeach associated with a main jack and an auxiliary jack. Each shutter is intended to be associated with an electrovalve 69 which serves either to connect the shutter to the general supply ducts 27, 28 or to isolate said shutter from these latter.

The general supply ducts 27, 28 extend to a central control station (not shown) which; comprises an oil reservoir or storage tank at atmospheric pressure and a' compressor whose input'is connected to said tank. The control station further comprises a reversing valve which is adapted to connect thedluct 27 to the delivery side of the compressor and to connect the duct 28 to the storage tank or conversely.

The control station can also comprise a position repeater (not shown) for each main jack, said repeater being branched off the pipe 63 which is connected to the upper chamber 61 of the main jack and being intended to measure the volume of oil discharged from said chamber when the corresponding shutter is operated, thus providing a means for remotely checking the position of said shutter.

In an alternative embodiment which is not illustrated,

the general supply ducts 27 and 28 can be dispensed with and the separatepipes 63, 64 which are associated with each main jack can be extended to the control station so as to terminate in a separate reversing valve which connects them respectively either to the compressor or to the storage tank.

The system operates as follows When the shutter 4 is in a predetermined position such as, for example, the horizontal position of withdrawal shown in FIG. 2, the operating rod 19 of the main jack is fully retracted within the body 17, both chambers of which are filled with oil at atmospheric pressure. The cover 26 of the hood 24 is closed. The operating rod 45 of the auxiliary jack 44 is also retracted and the gravity block 43 applies the roughened arm 42 of the lever 38 against the roughened cylinder 36, thus locking the body 17 of the main jack in the position which it had occupied at the end of the preceding operation. This positional locking; results from a virtual seizing action of a temporary nature and any risk of displacement is removed.

Furthermore, the ball 52 (shown in FIG. 6) is engaged in the particular recess 49 which corresponds to the position ofthe shutter 4 at that time and thus locks the abutment member 21 in the position which it had occupied at the end of the previous operation. It should be noted that the abutment member 21 itself does not display any tendency to change position by reason of the fact that its center of gravity is very close to its geometrical axis of rotation. Positional locking by means of the ball 52 is provided only as; a means of guarding against the effect of vibrations produced by the flow of water.

When it is desired to change the position of a given shutter of the movable gate system, the corresponding electromagnet 74 is supplied from the control station in order that the electrovalve 69 should establish a communication between the separate pipes 63, 64 and the general supply ducts 27, 28 the duct 28 is connected to the delivery side of the compressor and the duct 27 is connected to the storage tank. The lower chambers 62 and 65 of the two jacks are thus supplied with oil and the operating rod of the main jack passes out of the jack body and lifts the cover 26, whereupon the extremity of said operating rod then engages within the'abutment member 21 which is carried by the horse 5. As a result of the displacement of the piston which increases the volume of the compartment 62 of the main cylinder, the pressure of the oil discharged by the compressor increases only to a slight extent in this initial stage of displacement of the operating rod of the jack which has not yet come up against the abutment member of the horse. The pressure aforesaid, which also prevails within the lower compartment of the auxiliary jack, is not sufficient to lift the weight 43, with the result that the trunnion 36 (FIG. 4) remains locked and the orientation of the jack together with its operating rod remains invariable.

When the operating rod of the main jack comes into contact with the abutment member, said rod suddenly encounters a substantial resistance. The pressure immediately rises and attains the considerable value which is necessary in order to displace the shutter. The same pressure which prevails within the lower compartment of the auxiliary jack is then sufficient to ensure lifting of the weight 43, thereby releasing the trunnion 36 and enabling the jack 17 to modify its orientation.

As the compressor continues to discharge the highly compressed oil into the duct 28, the resistance of the shutter toits displacement in the upstream direction is overcome and the operating rod of the jack extends to an even greater distance from the cylinder, a high value of work being thus done by the jack rod in opposition to the water pressure. During this second stage of the displacement, the bottom end of the prop also moves in the upstream direction and is guided within the butter, the shapes of which result in lateral displacement of the prop under known conditions. When said bottom end of the prop has reached the position which ensures the downward return of this latter to the desired position, oil is no longer injected into the duct 28 and this latter is permitted to empty itself slowly. The pressure within the compartment 62 and within said duct 28 remains at a high value until the precise moment when the operating rod of the jack no longer supports the shutter, either because the prop is applied After having modified the position of the shutter in the manner which has just been explained, the operating rod of the piston must then be caused to withdraw. To this end, the position of the reversing valve of the control station is changed so as to connect the duct 28 to the storage tank and to connect the duct 27 to the delivery side of the compressor this accordingly produces within the upper chambers 61 and 62 of the two jacks a pressure which. is slightly higher than atmospheric pressure so as to cause the withdrawal of the operating rods of both jacks into their respective bodres.

Moreover, when the rod of the main jack has moved away from the orientable abutment member 21, said member has in turn been locked in position by the ball 52 which has engaged in another recess 49. Thus, the main jack body and the abutment member 21 will retain their respective orientations until the following operation is performed.

Once the operating rod 19 has fully withdrawn into the main jack body, the cover 26 of the hood 24 is again closed and the supply of current to the electromagnet 74 is cut off in order that the electrovalve should isolate the two jacks of the general supply ducts 27, 28. The two chambers of the two jacks remain filled with oil at a pressure which is practically equal to atmospheric pressure.

It is readily apparent that a number of shutters can be operated simultaneously by supplying the electromagnets of the corresponding electrovalves. There is shown in H6. 9 the application of the movable gate system in accordance with the invention to the spillway crest of a stationary dam of substantial height with a view to varying the height of said crest. It is known that the use of movable gates having small elements at the crest of a high dam has been ruled out up to the present time owing to the need to provide a service bridge which is considered to be an unattractive feature. By means of the invention, this objection can be dismissed.

In this application, the upstream plating of the shutter panel 81 is shaped in such a manner that, in the withdrawn position of the shutter, continuity of the profile of the spillway crest is maintained.

A cavity 82 is formed within the crest in order to house the hurter 16 and said cavity has an opening 83 in the downstream face of the crest in order to permit the flow of water. Similarly, the cavity 22 in which the main jack body 17 is housed has an extension in the form of a passageway 84 which has an opening on the downstream face at 85.

The shield hood 24 of the previous embodiment is no longer necessary since the cavity 22 is either protected by the shutter panel 81 when this latter is downwardly withdrawn or in the dry when the shutter is raised, seepage of water through the gate being permitted to pass through the passageway 84. In addition, the passageway just mentioned has the effect of removing any potential danger of deposition of silt within the cavity The gate system in accordance with the invention meets all objections of an aesthetic order which are made in regard to movable gates having small elements owing to the presence of a service bridge.

Moreover, the installation cost of the system is low in comparison with the cost of erection of a service bridge and operating carriage. Management and control of the gate system is made more flexible and less costly since a complete series of shutters can be remote-controlled within a very short time by a single operator, the speed of operations being limited only by the power of the compressor.

The system is further distinguished by a very high degree of reliability. The jacks and electrovalves or hydrovalvesare rugged units which have stood the test of time and experience. The operating rod of the main jack is exposed to the water only during the very brief period of operations and is immersed in oil for the rest of the time. The body of the main jack is housed in a closed cavity and its movements are not liable to be hindered by any depositionsof mud andsilt which can take place only at a very slow rate. If so required, it wouldin any case be an easy matter to remove these deposits periodically by suction. The positions of the shutters can readily be indicated from a distance. Between operations, the two chambers of the two jacks are practically at atmospheric pressure, thereby reducing the fatigue of components and virtually removing any danger of oil leakage.

Finally, by means of the locking devices provided by the invention, the engagement of the operating rod of the main jack in the orientable abutment member of the shutter is ensured although these two components are separated from each other between operations in order to protect the operating rod as has been stated earlier.

As is readily understood, the invention is not limited to the embodiments which have just been described and any number of alternative forms of execution can accordingly be contemplated without thereby departing from thescope of the invention. In particular, the invention is also applicable to shutters of the type com prising a shutter panel which is pivoted directly on the sill without interposition of a horse. In this case, the orientable abutment member is carried by the shutter panel.

The operations to be performed are sufficiently sim- .ple to permit of sequential control by means of a servomotor without any human agency. Variations in the level of water upstream of the shutters could, for example, be recorded by means of a float which would initiate in a predetermined order the necessary number of opening or closure operations for maintaining the up stream level between two permanently established limits. Known servomotor systems which are suitable for this purpose are too numerous to call for a preferential description of any one system.

I claim 1. A movable gate system for a hydraulic dam, said system being such as to comprise at least one shutter rotatably mounted with respect to a horizontal shaft attached to the floor or to the body of the dam, and a device for operating said shutter, wherein said operating device comprises an oscillating guide rotatably mounted with respect to a horizontal pin attached to the floor or to the body of the dam, a push-rod movable in rectilineal translational motion with respect to said guide, means for displacing the push-rod with respect to the guide and an abutment member which is orientable about a horizontal shaft attached to the shutter, said abutment member being adapted to receive the extremity of said push rod which is applied against said member during an operation of said shutter.

2. A system according to claim 1, wherein the oscillating guide and the movable push-rod are constituted respectively by the body and the piston rod of a main oil-actuated jack.

3. A system according to claim 2, wherein the two chambers defined by the piston within the body of the main jack are filled with oil and wherein said jack body is so dimensioned as to contain the entire piston rod in the withdrawn position of said piston.

4. A system according to claim 2, wherein the body of the main jack is disposed within a cavity formed in the body or the floor of the dam and wherein a shield hood is placed above said cavity, said hood being provided with a slot so as to permit the operating rod of the jack to pass therethrough.

5. A system according to claim 4, wherein the hood is provided with a hinged cover so as to close the slot through which the operating rod of the main jack is permitted to pass.

6. A system according to claim 2, wherein said system comprises a device for locking the body of the main jack and means operated in dependence on the supply of oil to said jack for controlling said locking device.

7. A system according to claim 6, wherein the locking device comprises an elbowed lever hinged about a horizontal pin, means adapted to produce action on the first arm of said lever in order to apply the second arm of the lever against a trunnion which is integral with the body of the main jack and an auxiliary oil-actuated jack which is supplied in parallel with the main jack and the operating rod of which controls the application means aforementioned so as to discontinue application of the second arm of said lever against said trunnion when the main jack is supplied at high pressure in order to displace the shutter.

8. A system according to claim 7, wherein he leverapplication means comprises a gravity block which is pivotally attached near the extremity of the first arm of said lever and has a cavity adapted to accommodate and support the operating rod of the auxiliary jack.

9. A system according to claim 6, wherein said system comprises a device for positional locking of the orientable abutment member of the shutter.

10. A system according to claim 9, wherein the center of gravity of the abutment member is located in the vicinity of its axis of rotation and said member has at least one cylindrical shaft-journal provided with a cavity in which is mounted a spring-controlled ball, and wherein a member attached to the shutter and having a cylindrical face coaxial with the shaft-journal is mounted close to the periphery of said joumal, said member being provided with spaced recesses having the shape of spherical cups each adapted to receive said ball.

1 l. A system according to claim 1, wherein the shutter comprises a horse rotatably mounted with respect to a horizontal shaft attached to the floor or to the body of the dam and a shutter panel pivoted about a horizontal shaft attached to said horse, wherein the abutment member is capable of moving about a horizontal shaft attached to said horse.

12. A system according to claim 4, wherein said system is mounted on the spillway crest of a stationary dam and wherein the cavity in which is mounted the body of the main jack is extended by a passageway having its opening on the downstream face of the crest.

w l 1* it 

1. A movable gate system for a hydraulic dam, said system being such as to comprise at least one shutter rotatably mounted with respect to a horizontal shaft attached to the floor or to the body of the dam, and a device for operating said shutter, wherein said operating device comprises an oscillating guide rotatably mounted with respect to a horizontal pin attached to the floor or to the body of the dam, a push-rod movable in rectilineal translational motion with respect to said guide, means for displacing the push-rod with respect to the guide and an abutment member which is orientable about a horizontal shaft attached to the shutter, said abutment member being adapted to receive the extremity of said push rod which is applied against said member during an operation of said shutter.
 2. A system according to claim 1, wherein the oscillating guide and the movable push-rod are constituted respectively by the body and the piston rod of a main oil-actuated jack.
 3. A system according to claim 2, wherein the two chambers Defined by the piston within the body of the main jack are filled with oil and wherein said jack body is so dimensioned as to contain the entire piston rod in the withdrawn position of said piston.
 4. A system according to claim 2, wherein the body of the main jack is disposed within a cavity formed in the body or the floor of the dam and wherein a shield hood is placed above said cavity, said hood being provided with a slot so as to permit the operating rod of the jack to pass therethrough.
 5. A system according to claim 4, wherein the hood is provided with a hinged cover so as to close the slot through which the operating rod of the main jack is permitted to pass.
 6. A system according to claim 2, wherein said system comprises a device for locking the body of the main jack and means operated in dependence on the supply of oil to said jack for controlling said locking device.
 7. A system according to claim 6, wherein the locking device comprises an elbowed lever hinged about a horizontal pin, means adapted to produce action on the first arm of said lever in order to apply the second arm of the lever against a trunnion which is integral with the body of the main jack and an auxiliary oil-actuated jack which is supplied in parallel with the main jack and the operating rod of which controls the application means aforementioned so as to discontinue application of the second arm of said lever against said trunnion when the main jack is supplied at high pressure in order to displace the shutter.
 8. A system according to claim 7, wherein he lever-application means comprises a gravity block which is pivotally attached near the extremity of the first arm of said lever and has a cavity adapted to accommodate and support the operating rod of the auxiliary jack.
 9. A system according to claim 6, wherein said system comprises a device for positional locking of the orientable abutment member of the shutter.
 10. A system according to claim 9, wherein the center of gravity of the abutment member is located in the vicinity of its axis of rotation and said member has at least one cylindrical shaft-journal provided with a cavity in which is mounted a spring-controlled ball, and wherein a member attached to the shutter and having a cylindrical face coaxial with the shaft-journal is mounted close to the periphery of said journal, said member being provided with spaced recesses having the shape of spherical cups each adapted to receive said ball.
 11. A system according to claim 1, wherein the shutter comprises a horse rotatably mounted with respect to a horizontal shaft attached to the floor or to the body of the dam and a shutter panel pivoted about a horizontal shaft attached to said horse, wherein the abutment member is capable of moving about a horizontal shaft attached to said horse.
 12. A system according to claim 4, wherein said system is mounted on the spillway crest of a stationary dam and wherein the cavity in which is mounted the body of the main jack is extended by a passageway having its opening on the downstream face of the crest. 